英文:
data manipulation after file (excel) input in shiny
问题
I have an Excel dataset that I want to manipulate after uploading it. Let's say in this case I would like to add a newcolumn <- 3, how can I get around with this? many thanks in advance.
ui.r
library(shiny)ui <- fluidPage(titlePanel("daily data manipulation"),sidebarLayout(sidebarPanel(fileInput('file1', 'Choose xlsx file',accept = c(".xlsx"))),mainPanel(tableOutput(outputId = "mytable"))))
server.r
server <- function(input, output) {data <- reactive({inFile <- input$file1if(!is.null(inFile)) {readxl::read_excel(inFile$datapath)}})dat <- data()output$mytable <- renderTable({dat$newcolumn <- 3})}
英文:
I have an Excel dataset that I want to manipulate after uploading it. Let's say in this case I would like to add a newcolumn <- 3, how can I get around with this? many thanks in advance.
ui.r
library(shiny)ui <- fluidPage(titlePanel("daily data manipulation"),sidebarLayout(sidebarPanel(fileInput('file1', 'Choose xlsx file',accept = c(".xlsx"))),mainPanel(tableOutput(outputId = "mytable"))))
server.r
server <- function(input, output) {data <- reactive({inFile <- input$file1if(!is.null(inFile)) {readxl::read_excel(inFile$datapath)}})dat <- data()output$mytable <- renderTable({dat$newcolumn <- 3})}
答案1
得分: 1
Reactive expressions can only be consumed in a reactive context, so dat <- data() should be moved inside renderTable.
此外，在添加新列之前检查反应性值是否为null可以确保在用户上传Excel文件之前不会呈现新列。
英文:
Reactive expressions can only be consumed in a reactive context, so dat <- data() should be moved inside renderTable.
server <- function(input, output, session) {data <- reactive({inFile <- input$file1if(!is.null(inFile)) {readxl::read_excel(inFile$datapath)}})output$mytable <- renderTable({dat <- data()if(!is.null(dat)){dat$newcolumn <- 3dat}})}
Also, checking if the reactive value is null before adding the new column ensures that until the user uploads an excel file the new column will not be rendered.
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